Note: Descriptions are shown in the official language in which they were submitted.
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THERAPEUTIC MATTRESS ASSEMBLY
This is a divisional of Canadian National Phase Patent Application
Serial No. 2,428,225 filed on November 6, 2001.
FIELD OF THE INVENTION
The invention relates generally to inflatable mattress systems, and
particularly to a mattress assembly combining an inflatable substrate and a
foam
support surface.
BACKGROUND OF THE INVENTION
Inflatable mattresses are used in hospital rooms, old age homes, and
other applications in which a person is required to spend long periods of time
restricted to a bed. A common problem for patients requiring such long-term
care is
the development of decubitus ulcers, or bed sores, caused by excessive
pressure
applied to a patient's contact points. A patient's weight on a bed can cause a
counter
force to be applied to the patient's body from the bed at points where the
patient's
body contacts the bed. Although contact points can be present across the body,
it is
common for sick and disabled individuals who are bed bound to develop tissue
damage on the heels of the feet, on the ankle, and/or on other parts of the
body. This
tissue damage to the heels is generally the result of an individual lying in a
supine
position where the heels bear the weight of the legs on the surface of the
mattress.
Alternatively, if the individual is in a sidelying position, the ankle will
bear the weight
of the legs against the mattress. Often, this pressure exceeds the ability of
the
capillaries to circulate blood to the cells which results in an isohemic
condition.
Lacking blood supply, these cells die causing the tissue damage.
In known continuous flow, low air loss mattresses, air is used to expand
the mattress to a desired pressure. Air is allowed to escape the air mattress
through
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small holes located on the top of the mattress. These holes serve to maintain
a
constant mattress pressure against the patient and provide air flow between
the
patient and the mattress to remove humidity created by the patient's body.
This
feature keeps the mattress dry, accelerates the healing process, and helps
prevent
bed sores. An example of one such air loss system is disclosed in U.S. Patent
No. 4,896,389 to Chamberland.
Leg elevation is a commonly employed method of removing pressure
from heels in the supine position and from the ankles in a sidelying position.
This is
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frequently. accomplished by placing pillow or wedges under and/or between the
legs of the individual on the mattress.
A mattress that includes multiple inflatable air chambers to assist in
relieving pressure from contact points for bed bound patients is disclosed in
U.S.
Patent No. 4,953,247 to Hasty. These inflatable mattresses have varied the
pressure in specific chambers to help contour the mattress and apply equal
force
throughout the patient's body.
U.S. Patent No. 5,666,681 to Meyer et al. discloses a device for relieving
pressure on a patient's heels and/or ankles by employing multiple air chambers
under.the patient's heels that are located within the mattress. A first air
chamber
directly under the heels deflates allowing the heels to sink down into the
mattress
while the pressure of a second forwardly adjacent air chamber increases to
lift the
calves to further reduce the stress on the heels.
SUMMARY OF INVENTION
The present invention allows for distribution of pressure across a patient's
body, adjustment calf elevation for the further reduction of stress on a
patient's
heels and ankles, rotation of a patient laterally on the mattress, and
controlled
inflation of alternating cylinders within the substrate assembly.
The present invention incorporates a continuous flow, low air loss mattress
with an overlay made of visco-elastic foam and a calf lift bladder to provide
the
benefits associated with leg elevation while avoiding the problems associated
with
existing methods. This pneumatically powered calf elevator serves to
reduce/relieve pressure against the heels and ankles by lifting them from the
surface of the mattress.
In one embodiment, the invention provides a therapeutic mattress
assembly with various features designed to relieve pressure for a patient. The
therapeutic mattress itself consists of a bottom cover and a separable top
cover
that form an enclosure. Within the bottom cover and the top cover is a
substrate
assembly, a calf lift bladder, and an overlay assembly. The substrate assembly
is
made up of multiple cylinders, each having elongated chambers that extend
laterally across the width of the mattress. The cylinders are aligned side by
side,
directly adjacent to each other, along the length of the mattress. Each
cylinder is
an individually sealed chamber in which the pressure can be varied. The upper
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surfaces of the air cylinders are perforated to provide the low air loss
effect. The
cylinders are expandable by air pressure to varying heights to disperse the
pressure against the body of the patient. The cylinders also include multiple
layers of foam positioned within each cylinder that act to support the patient
when
the cylinders are deflated.
The calf lift bladder is a single inflatable chamber located near the foot end
of the mattress and extending across the width of the therapeutic mattress.
The
upper surface of the therapeutic mattress is flat when the calf lift bladder
is
deflated. When inflated, the calf lift bladder creates a bulge in the
therapeutic
mattress, raising the patient's calves relieving the pressure on the patient's
heels
and./or ankles. The calf lift bladder car, be set to any position between the
fully
inflated and fully deflated positions to properly accommodate the patient.
However, in other embodiments the calf lift bladder could be located between
any
of the components of a multi-component mattress or the bladder could lie on
top
of the mattress above the upper layer.
The position of the calf lift bladder can be adjusted along the length of the
therapeutic mattress according to the height of the patient. The calf lift
bladder, is
also preferably positioned between the overlay assembly and the plurality of
cylinders. The positioning of the calf lift bladder is advantageous because it
does
not interfere with elements located within the substrate assembly. In
addition,
unlike the pillow method, the calf bladder does not introduce additional items
to
the surface of the bed which is generally undesirable. Further, the degree of
calf
elevation is easily adjusted by the air pressure directed to the calf lift
bladder,
whereas ordinary pillows have physical properties of density and thickness
which
may not be optimal for individual needs.
The lateral rotation assembly includes first and second lateral rotation
wedges that extend the length of the mattress and that are located under the
therapeutic mattress. Each lateral rotation wedge can be inflated to a wedge
shape
with the narrowest portion of the wedge in the center of the mattress. These
lateral rotation wedges can be individually inflated to raise a respective
side of the
mattress. When the lateral rotation wedge on one side of the mattress is
inflated
the mattress is tilted creating a slant along one half of the width of the
mattress.
Each lateral rotation wedge can tilt its respective half of the mattress to an
angle
of approximately 30 degrees from the center of the mattress. When the mattress
is
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tilted from one side to the other, the patient is also rotated to alternate
pressure
caused by the patient's weight. The overlay assembly has inflatable bolsters,
or
side rails, located along the sides of the overlay assembly to aid in securing
the
patient on the mattress while one side is being raised. Preferably, only the
bolster
positioned opposite the inflated lateral rotation bladder is inflated.
The overlay lies above the main air bladders and preferably includes a
visco-elastic foam cushion. The overlay provides a smooth surface for the
patient
to rest on and distributes the pressure between the patient and the air
cylinders.
The visco-elastic foam material possesses specific thermally activated
properties
which the conform the surface to the shape of the patient's body. This feature
also
distributes the weight of the patient over a greater area.
The mattress also includes a blower assembly that includes a blower, a
valve assembly, and a controller. The blower is the air source for and is in
selective fluid flow connection with the air cylinders, the lateral rotation
wedges,
the bolsters, and the calf lift bladder. The valve assembly selectively
distribute
the air flow from the blower to either the air cylinders or the lateral
rotation wedge
and the bolsters. In addition, the valve assembly selectively distributes air
to the
calf bladder independent of the air cylinders, and the lateral rotation wedges
and
bolsters. The controller regulates the valve assembly and the blower provides
and
adjusts the air pressure supply. The controller contains a microprocessor and
can
be programmed to increase the air pressure in specific cylinders to alternate
the
pressure on the patient.
Another feature of the mattress is the low air loss system that allows air to
reach surfaces of the patient's body that contact the mattress. The blower
provides a constant air flow to the cylinders while the upper surface of the
cylinders are perforated to permit the air to escape. Because of this constant
flow,
the cylinders can maintain a desired air pressure even though air is leaking
through the upper surface of the cylinders. The overlay assembly is also
permeable and allows the air to flow through and reach the patient.
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In another embodiment, the invention provides a therapeutic mattress
assembly for supporting a patient, the therapeutic mattress assembly
comprising: a
low air loss mattress for supporting the patient, the mattress having first
and second
elongated sides; a plurality of selectively inflatable cylinders together
defining a
substrate adapted to support the patient; each of the plurality of cylinders
comprising:
cylinder walls; an internal chamber defined at least in part by the cylinder
walls; and a
layer of foam within the internal chamber; a layer of foam atop the plurality
of
selectively inflatable cylinders; and at least one selectively inflatable
bladder atop the
plurality of selectively inflatable cylinders.
In a further embodiment, the invention provides a mattress assembly for
supporting a body, the mattress assembly comprising: a low air loss mattress
including a first low air loss cylinder having a first cylinder wall defining
a plurality of
holes allowing air to flow from the first low air loss cylinder, and a second
low air loss
cylinder having a second cylinder wall defining a plurality of holes allowing
air to flow
from the second low air loss cylinder; a blower connected to the first and
second low
air loss cylinders; a controller connected to the blower and operable to
control air
supply to inflate the first and second low air loss cylinders in an
alternating manner,
wherein in one state, air is supplied to expand the first low air loss
cylinder while the
second low air loss cylinder deflates, and wherein in another state, air is
supplied to
expand the second low air loss cylinder while the first low air loss cylinder
deflates; a
first layer of visco-elastic foam atop the first and second low air loss
cylinders and
through which air escaping from the first and second low air loss cylinders
passes
toward the body; and a second layer of foam within each of the first and
second low
air loss cylinders.
Other features and advantages of the invention will become apparent to
those skilled in the art upon review of the following detailed description,
claims, and
drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. I is a schematic view illustrating a therapeutic mattress assembly
embodying the present invention.
Fig. 2 is an exploded view illustrating the therapeutic mattress assembly
shown in Fig. 1.
Fig. 3 is a perspective view illustrating a mattress of the therapeutic
mattress assembly shown in Fig. 1.
Fig. 4 is a top view illustrating the mattress shown in Fig. 3.
Fig. 5 is a cross-sectional view taken along line 5-5 in Fig. 4, illustrating
a
cylinder in the inflated condition.
Fig. 6 is a cross-sectional view taken along line 6-6 in Fig. 4, illustrating
the cylinder in the inflated and deflated condition(in hidden lines).
Fig. 7 is a cross-sectional view taken along line 7-7 in Fig. 4.
Fig. 8 is an end view illustrating the therapeutic mattress assembly shown
in Fig. 1, illustrating a calf lift bladder in the deflated position.
Fig. 9 is an end view of the therapeutic mattress assembly shown in Fig. 1,
illustrating the calf lift bladder in the inflated position.
Fig. 10 is an end view of the therapeutic mattress assembly of Fig. 1,
illustrating a first lateral rotation wedge in the inflated position.
Fig. 11 is an end view of the therapeutic mattress assembly of Fig. 1,
illustrating the second lateral rotation wedge in the inflated position.
Before one embodiment of the invention is explained in detail, it is to be
understood that the invention is not limited in its application to the details
of
construction and the arrangements of the components set forth in the following
description or illustrated in the drawings. The invention is capable of other
embodiments and of being practiced or being carried out in various ways. Also,
it
is understood that the phraseology and terminology used herein is for the
purpose
of description and should not be regarded as limiting. The use of "including"
and
"comprising" and variations thereof herein is meant to.encompass the items
listed
thereafter and equivalents thereof as well as additional items. The use of
"consisting of' and variations thereof herein is meant to encompass only the
items
listed thereafter. The use of letters to identify elements of a method or
process is
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simply for identification and is not meant to indicate that the elements
should be
performed in a particular order.
DETAILED DESCRIPTION
Figs. 1-I1 illustrate a therapeutic mattress assembly 10 embodying the
invention. With reference to Fig. 1, the therapeutic mattress assembly 10
includes
a mattress 14, and a lateral rotation assembly 18 located under the mattress
14 to
assist in turning a patient on the mattress 14. The therapeutic mattress
assembly
also includes a blower assembly 20 that includes"a blower 22, a valve assembly
10 26 connected to the blower 22, and a controller 30 connected between the
blower
22 and valve assembly 26 to regulate the air flow to the mattress 14 and the
lateral
rotation assembly 18.
With reference to Figs. 2-4, the mattress 14 includes a bottom cover 38
and a top cover 42 detachably connected to the bottom cover 38 to form an
enclosure. In the preferred embodiment, the perimeter of the top cover 42 is
detachably connected to the perimeter of the bottom cover 38 by a zipper 46.
The
bottom cover 38 defines an upwardly facing cavity with four interconnected
side
walls connected to a bottom wall. The bottom cover 38 includes a plurality of
mating snaps 50 located on both the interior and the exterior of the side
walls.
The function of these mating snaps 50 will be discussed below. The top cover
42
is preferably made from a high moisture vapor transfer (MVT) material that
specifically will allow the transfer of air but is moisture resistant_
The mattress 14 includes a substrate assembly 54 positioned within the
enclosure formed by the top and bottom covers 42, 38. The substrate assembly
54
includes a plurality of elongated cylinders 58 extending the width of the
bottom
cover 38 and positioned side by side along the length of the bottom cover 38.
As
best shown in Figs: 4-7, each cylinder 58 includes a sleeve- 62 preferably
made
from an air impermeable material such as urethane coated nylon.. The sleeve 62
is
a completely enclosed casing that defines an interior cavity. The top surface
of
the sleeve 62.includes multiple pin-sized holes 66 preferably spaced about 3
inches apart acfoss the length of the sleeve 62.
As shown in Fig. 5, the cylinder 58 also includes a left base foam layer 70
and a right base foam layer 74 positioned adjacent to the left base foam layer
70,
both positioned within the sleeve 62. The left and right base foani layers 70,
74
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extend approximately the entire length of the sleeve 62 and each extend about
one
half of the width of the sleeve 62: Preferably, the left and right base foam
layers
70, 74 are about 1'/4 inches thick and made of reticulated foam. The cylinder
58
also includes an intermediate foam layer 78 positioned above the left and
right
base foam layers 70, 74. The intermediate foam layer 78 extends approximately
the entire length and width of the sleeve 62. Preferably, the intermediate
foam
layer 78 is about 1 inch thick and is made of high resilience foam. The
cylinder
58 also includes a top foam layer 82 positioned on top of the intermediate
foam
layer 78, extending approximately the entire length and width of the sleeve
62.
Preferably, the top foam layer 82 is about I %z inches thick and is made of
visco-
elastic foam.
The visco-elastic foam material possesses specific thermally activated
properties which causes the foam surface to conform to the shape of the
patient's
body. Specifically, the visco-elastic foam has a lower compression coefficient
at
an elevated temperature as compared to the compression coefficient at a cooler
temperature. The body heat of the patient acts to soften the visco-elastic
foam
directly supporting the body while the part of the cushion not supporting the
body
remains in a firmer condition. This feature also allows for a more equal
distribution of the patient's weight over a greater surface area.
The sleeve 62 also includes a first, second, and third horizontal gusset 86,
90, 94, and a vertical gusset 98 positioned within the sleeve 62 to provide
the
cylinder 58 with a substantially rectangular shape when inflated. The first
horizontal gusset 86 is located directly between the left and` right base foam
layers
70, 74 and the intermediate foam layer 78 and is connected between the
interior
side walls of the sleeve 62:' The second horizontal gusset 90 is located
directly
between the intermediate foam layer 78 and the top foam layer 82 and is
connected between the interior side walls of the sleeve 62. The third
horizontal
gusset 94 is located directly above the top foam layer 82 and is connected
between
the interior side walls of the sleeve 62. The third horizontal gusset 94
substantially defines an air cavity 102 between the third horizontal gusset 94
and
the top interior wall of sleeve 62. The vertical gusset 98 is positioned
between the
left and right base foam layers 70, 74 and is connected between the first
horizontal
gusset 86 and the bottom interior wall of the sleeve 62. Preferably, the
horizontal
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gussets 86, 90, 94 are substantially parallel to each other and the vertical
gusset 98
is generally perpendicular to the horizontal gussets 86, 90, 94.
As shown in Fig. 7, the cylinder 58 also includes two tabs 106, each
connected to one end of the cylinder 58. The tabs 106 are positioned near the
top
of the ends of the sleeve 62 and extend generally away from the sleeve 62. The
tabs 106 are preferably made from the same material as the sleeve 62. The
cylinder 58 also includes snaps 110 located on the outward end of each of the
tabs
106. The snaps 110 are detachably connectable to mating snaps 50 located on
the
interior face of the bottom cover 38 side wall. The mating snaps 50 fixably
position the cylinders 58 at equal distances along the length of the bottom
cover
38. It should be noted that snaps are only the preferred device used for
connection. Other methods of connection may also be used, such as hook and
loop fasteners, buttons, zippers, laces, and the like. As best shown in Fig.
6, the
cylinders 58 also include a cylinder coupling 114 located on one end of the
cylinder 58 to facilitate the transfer of air from the blower assembly 20 into
the air
cavity 102 of the sleeve 62 without substantial loss to the atmosphere.
The mattress 14 is configured to provide a low air loss system that allows
air to reach surfaces of the patient's body that contact the mattress 14 from
the
inflated cylinders 58. The blower 22 provides a constant air flow to the
cylinders
58 while the upper surface of the cylinders 58 are perforated to permit the
air to
escape. The cylinders 58 can maintain a constant desired air pressure even
though
air is slowly leaking through the upper surface of the cylinders 58 because
air is
constantly circulated to.the cylinders 58.
Referring to Figs. 2 and 4-7, the mattress 14 also includes an overlay
assembly 118 positioned above the substrate assembly 54 and between the top
and
bottom covers 42, 38. The overlay assembly 118 includes an overlay cover 122
having a top surface and a bottom surface connected along their respective
perimeters defining an internal cavity. Preferably, the overlay cover 122 is
made
from two types of material. The perimeter portion of the overlay cover 122 is
30- preferably made from a non-resilient nylon fabric and the central portion
of the
overlay cover 122 is preferably made from an air permeable, four way stretch
fabric that allows for the expansion of the cylinders 58 and the passage of
air from
the cylinders 58 to the patient. The overlay cover 122 includes a plurality of
cover
snaps 126 positioned uniformly around the perimeter of the overlay cover 122
and
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attached to the perimeter portion. The cover snaps 126 are detachably
connectable to mating snaps 50 located on the exterior face of the bottom
cover 38
side wall. The cover snaps 126 secure the overlay assembly 118 to the bottom
cover 38 and fixably position the overlay assembly 118 over the cylinders 58.
The overlay assembly 118 also includes a foam cushion 130 positioned
within the cavity of the overlay cover 122. The foam cushion 130 is preferably
approximately 1 inch thick and is made of visco-elastic foam material. The
foam
cushion 130 includes a plurality of holes substantially aligned on center with
the
pin-sized holes 66 of the cylinders 58 to facilitate the flow of air through
the foam
cushion 130 to the patient. Preferably, a die cutting process is used to
remove
plugs of material from the foam cushion 130 to form an array of properly
aligned
%4 inch diameter holes. The array of holes preferably only extends to about 4
inches from the perimeter of the foam cushion. The size and number of holes
cut
into the foam cushion 130 are limited to assure a sufficient percentage of
foam
remains to provide adequate support to the patient.
The overlay assembly 118 also includes a first bolster 134 and second
bolster 138, positioned within the foam cushion 130 along opposite ends of the
foam cushion 130. The first and second bolsters 134, 138 are inflatable
bladders
that extend approximately the entire length of the foam cushion 130. Each
bolster
134, 138 includes a bolster coupling 142 that allows air to be transferred
from the
blower assembly 20 to inflate the bolsters 134, 138. Preferably, the bolsters
134,
138 are approximately 4 inches wide and have a negligible thickness in the
deflated condition. The bolsters 134, 138 are located approximately 1 inch
from
the edge of the foam cushion. Preferably, the bolsters 134, 138 are inserted
into
the foam cushion 130 by splitting the edge of the foam cushion 130 into two
flaps
of equal thickness. After placing the deflated bolsters 134, 138 within the
approximately 5 inch deep cut, the two equally thick flaps are refastened
together
along the common edge by a glue or similar adhesive. Once inflated, the
bolsters
134, 138 cross-sections will expand to a generally circular shape.
As shown in Figs. 2-4 and 8-9, the mattress 14 also includes a calf lift
bladder 146 positioned between the cylinders 58 and the overlay assembly 118.
The calf lift bladder 146 includes a single inflatable chamber 150 located
near the
foot end of the mattress 14 and extending across the width of the mattress 14.
The
calf lift bladder 146 includes a calf lift coupling 154 that facilitates the
air flow
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from the blower assembly 20 into the inflatable chamber 150: The position of
the
calf lift bladder 146 can be adjusted along the length of the therapeutic
mattress 14
according to the height of the patient. The thickness of the calf lift bladder
146 is
negligible when the calf lift bladder 146 is deflated. When inflated, the calf
lift
5 bladder 146 creates a bulge in the therapeutic mattress 14, raising the
patient's
calves relieving the pressure on the patient's heels and/or ankles. The calf
lift
bladder 146 can be set to any position between the fully inflated and fully
deflated
positions to properly accommodate the patient.
As shown in Figs. 2, 10, and 11, the lateral rotation assembly 18 includes
10 first and second lateral rotation wedges 158, 162 extending the length of
the
mattress 14 and located under the mattress 14. The lateral rotation wedges
158,
162 each include a wedge coupling 166 that allows air to flow into the lateral
rotation wedges 158, 162 from the blower assembly 20. Each lateral rotation
wedge 158, 162 can be inflated to a wedge shape with the narrowest portion of
the
wedge in the center of the mattress 14 and the widest portion of the wedge
near
the outer edge of the mattress 14. The upper surface of the wedge 158, 162 is
preferably a convex surface with the maximum height positioned toward the
outer
edge. More preferably, the first one third of the convex surface has a
decreasing
positive slope ending at the maximum height. The following two thirds of the
lateral inflation wedge 158, 162 has an increasing negative slope terminating
at
the center of the mattress 14. These lateral rotation wedges 158, 162 can be
individually inflated to raise each respective side of the mattress 14 to
effectively
turn a patient on their side to alternate the part of the body which supports
the
weight. Some patients may also require lateral rotation to drain a buildup of
fluid
in the lungs. Each lateral rotation wedge 158, 162 can tilt its respective
half of the
mattress 14 to an angle of approximately 30 degrees from the center of the
mattress 14. The bolsters 134, 138 of the overlay assembly 118 also inflate
with
the lateral rotation wedges 158, 162 to secure the patient on the mattress 14
while
one side is being raised. Preferably, only the bolster positioned opposite the
inflated lateral rotation bladder is inflated.
Referring to Fig. 1, the blower 22 is the air source for and is in fluid flow
connection with air cylinders 58, the lateral rotation wedges 158, 162, the
bolsters
134, 138, and the calf lift bladder 146. The valve assembly 26 includes valve
170
that is in fluid flow connection with the blower 22 and which selectively
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distributes the air flow from the blower 22 to the air cylinders 58, the
lateral
rotation wedges 158, 162 and the bolsters 134, 138, and thecalf lift bladder
146.
The valve assembly 26 includes first and second cylinder hoses 174, 178, first
and
second lateral rotation hoses 190, 194, and first and second bolster hoses
182, 186
that are fluidly connected to the first and second lateral rotation hoses 190,
194,
respectively.
The first cylinder hose 174 is in fluid flow connection between the valve
170 and approximately %2 of the cylinder couplings 114 of the cylinders 58.
Specifically, the first cylinder hose 174 supplies air flow to alternating
cylinders
58 along the length of the mattress 14. The second cylinder hose 178 is in
fluid
flow connection between the valve 170 and the cylinder couplings 114 of the
remaining cylinders 58 not coupled to the first cylinder hose 174.
The first lateral rotation hose 190 is in fluid flow connection between the
valve 170 and the wedge coupling 166, and the second lateral rotation hose 194
is
in fluid flow connection between the valve 170 and the wedge coupling 166 of
the
second lateral rotation wedge 162. The first bolster hose 182 is fluidly
connected
to the second lateral rotation hose 194, and the second bolster 186 is fluidly
connected to the first lateral rotation hose 190. The bolster hoses 182, 186
are
coupled to the lateral rotation hoses 190, 194 such that only the opposite
bolster
134, 138 inflates with a lateral rotation wedge 158, 162.
The valve 170 also independently controls the inflation and deflation of
the calf lift bladder. The valve assembly 26 includes a calf lift hose 202
that is in
fluid flow connection between the valve 170 and the calf lift coupling 154.
The controller 30 regulates the valve assembly 26, and the blower 22
based upon desired mattress conditions. The controller 30 contains a
microprocessor and can be programmed to increase or decrease the air pressure
in
the cylinders 58, the calf lift bladder 146, the lateral rotation wedges 158,
162, and
the bolsters 134, 138.
In operation, the controller 30 manipulates the therapeutic mattress
assembly 10 between multiple modes of operation. Specifically, the therapeutic
mattress assembly 10 functions in four modes of operation: (1) Power on; (2)
Power off; (3) Lateral rotation; and (4) Alternating pressure. The modes of
operation will be discussed in further detail below.
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In the power on mode, as best shown in Figs. 5-7, the controller 30
activates the blower 22 to create an air flow to the valve assembly 26 at a
desired
pressure. The controller 30 also manipulates the valve 170 to allow the air to
flow
only to the first and second cylinder hoses 174, 178. The air then flows
through
the cylinder couplings 114-into all of the cylinders 58. The air flow
increases the
pressure within each cylinder 58 causing each of the cylinders 58 to expand. A
constant pressure is maintainable within each of the cylinders 58 because
although
air is allowed to escape-through the pin-sized holes 66 in the cylinder
sleeves 62.
The air that escapes the cylinders 58 is forced through the air permeable
overlay
cover 122 and the holes in the foam cushion 130. Finally, the air is forced
through
the top cover 42 and against the body of the patient to remove moisture and
encourage healing.
In the power off mode, as shown in broken lines in Fig. 6, the blower 22
does not provide an increased air pressure and the air within the therapeutic
'15 mattress assembly 10 is released. This mode may occur during transport of
a
mattress assembly 10 where an independent power source is not available, or
during a power outage. Because the cylinders 58 are not supplied with an
increased air pressure, the cylinders 58 are in the deflated position and the
interior
surface of the cylinder sleeve 62 is positioned directly against the third
horizontal
gusset 94 of the cylinder 58. As opposed to other low air flow mattresses. in
the
power off mode, the patient will still receive adequate pressure distributing
support from the mattress 14. In this situation the body's weight is supported
essentially by the foam cushion 130 of the overlay assembly 118 and the top
foam
layer 82, the intermediate foam layer 78, and the base foam layers 70, 74 of
each
of the cylinders 58.
As best shown in Figs. 10 and 11, the lateral rotation mode operates from
the power off mode to allow for proper positioning of the mattress 14. In the
lateral rotation mode, the controller 30 activates the blower 22 to create an
air
flow to the valve assembly 26 at a desired pressure. The controller 30 also
manipulates the valve 170 to allow the air to flow only to bolster hoses 182,
one
of either the first 190 or second lateral rotation hose 194 and the respective
bolster
hose 182, 186. The air then flows through the wedge coupling 166 into one of
the
lateral rotation wedges 158, 162 expanding the wedge into the inflated
position
and through one of the bolster couplings 142 into the respective bolster 134,
138
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causing the respective bolster 134, 138 to expand to the inflated position.
The
inflated lateral rotation wedge raises the respective end of the mattress 14
to rotate
the patient on the mattress 14. The inflated bolster 134, 138 secures the
patient on
the mattress 14 and aids in preventing the patient from rolling off of the
mattress
14. If the patient needs to be turned in the other direction, the controller
30
activates the valve 170 direct the air flow to the deflated lateral rotation
wedge
158, 162 and bolster 134, 138.
In the alternating pressure mode, the controller 30 activates the blower 22
to create an air flow to the valve assembly 26 at a desired pressure.
Referring to
Fig. 2, the controller 30 also manipulates the valve 170 to allow the air to
flow
only to the first cylinder hose 174. The air then flows through the cylinder
couplings 114 into only the cylinders 58 connected to the first cylinder hose
174.
The air flow increases the pressure within each of these cylinders 58 causing
them
to expand. A constant pressure is maintained within each of these cylinders 58
in
a mariner similar to that explained above. To relieve the pressure applied to
the
body by the inflated cylinders 58 over a period of time, the controller 30
manipulates the valve 170 to release the air from the inflated cylinders 58
and
allow the air to flow into the second cylinder hose 178. The air will then
flow
through the cylinder couplings 114 into only the cylinders 58 connected to the
second cylinder hose 178, specifically, the previously deflated cylinders 58.
The
controller 30 can be programmed to set a period of time between alternating
conditions, or otherwise the rotation can be done at any time desired by the
operator.
In any of the above mentioned modes, the controller 30 can independently
adjust the valve 170 to inflate or deflate the calf lift bladder 146. As shown
in
Figs. 1, 3, 8, and 9, the adjustment of the pressure communicated to the calf
lift
bladder 146 directly adjusts the distance that ankles and/or heels are lifted
above
the bed. Specifically, the controller 30 activates the blower 22 to create an
air
flow to the valve 170 at a desired pressure. The controller 30 also
manipulates the
valve 170 to allow the air to flow through the calf lift hose 202 to the calf
lift
coupling 154. The air then flows through the calf lift coupling 154 into the
calf
lift bladder 1.46. The air flow increases the pressure within the calf lift
bladder
146 causing it to expand and raise a patient's feet. Alternatively, if the
operator
wishes to lower the patient's feet, the controller 30 adjusts the valve 170 to
release
CA 02762006 2011-12-20
67363-131 OD
td
air from the calf lift bladder 146. The released air lowers the pressure
within the
calf lift bladder 146 causing the patient's feet to lower.
